1
|
Li M, Cai Z, Song S, Yue X, Lu W, Rao S, Zhang C, Xue C. EcCas6e-based antisense crRNA for gene repression and RNA editing in microorganisms. Nucleic Acids Res 2024; 52:8628-8642. [PMID: 38994565 PMCID: PMC11317134 DOI: 10.1093/nar/gkae612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 06/25/2024] [Accepted: 06/28/2024] [Indexed: 07/13/2024] Open
Abstract
Precise gene regulation and programmable RNA editing are vital RNA-level regulatory mechanisms. Gene repression tools grounded in small non-coding RNAs, microRNAs, and CRISPR-dCas proteins, along with RNA editing tools anchored in Adenosine Deaminases acting on RNA (ADARs), have found extensive application in molecular biology and cellular engineering. Here, we introduced a novel approach wherein we developed an EcCas6e mediated crRNA-mRNA annealing system for gene repression in Escherichia coli and RNA editing in Saccharomyces cerevisiae. We found that EcCas6e possesses inherent RNA annealing ability attributed to a secondary positively charged cleft, enhancing crRNA-mRNA hybridization and stability. Based on this, we demonstrated that EcCas6e, along with its cognate crRNA repeat containing a complementary region to the ribosome binding site of a target mRNA, effectively represses gene expression up to 25-fold. Furthermore, we demonstrated that multiple crRNAs can be easily assembled and can simultaneously target up to 13 genes. Lastly, the EcCas6e-crRNA system was developed as an RNA editing tool by fusing it with the ADAR2 deaminase domain. The EcCas6e-crRNA mediated gene repression and RNA editing tools hold broad applications for research and biotechnology.
Collapse
Affiliation(s)
- Mutong Li
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Zhaohui Cai
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Shucheng Song
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Xinmin Yue
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Wenyu Lu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Shuquan Rao
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China
| | - Chuanbo Zhang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Chaoyou Xue
- Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Center of Technology Innovation for Synthetic Biology, Tianjin 300308, China
| |
Collapse
|
2
|
Batista M, Langendijk-Genevaux P, Kwapisz M, Canal I, Phung DK, Plassart L, Capeyrou R, Moalic Y, Jebbar M, Flament D, Fichant G, Bouvier M, Clouet-d'Orval B. Evolutionary and functional insights into the Ski2-like helicase family in Archaea: a comparison of Thermococcales ASH-Ski2 and Hel308 activities. NAR Genom Bioinform 2024; 6:lqae026. [PMID: 38500564 PMCID: PMC10946056 DOI: 10.1093/nargab/lqae026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 02/19/2024] [Accepted: 02/27/2024] [Indexed: 03/20/2024] Open
Abstract
RNA helicases perform essential housekeeping and regulatory functions in all domains of life by binding and unwinding RNA molecules. The Ski2-like proteins are primordial helicases that play an active role in eukaryotic RNA homeostasis pathways, with multiple homologs having specialized functions. The significance of the expansion and diversity of Ski2-like proteins in Archaea, the third domain of life, has not yet been established. Here, by studying the phylogenetic diversity of Ski2-like helicases among archaeal genomes and the enzymatic activities of those in Thermococcales, we provide further evidence of the function of this protein family in archaeal metabolism of nucleic acids. We show that, in the course of evolution, ASH-Ski2 and Hel308-Ski2, the two main groups of Ski2-like proteins, have diverged in their biological functions. Whereas Hel308 has been shown to mainly act on DNA, we show that ASH-Ski2, previously described to be associated with the 5'-3' aRNase J exonuclease, acts on RNA by supporting an efficient annealing activity, but also an RNA unwinding with a 3'-5' polarity. To gain insights into the function of Ski2, we also analyse the transcriptome of Thermococcus barophilus ΔASH-Ski2 mutant strain and provide evidence of the importance of ASH-Ski2 in cellular metabolism pathways related to translation.
Collapse
Affiliation(s)
- Manon Batista
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | | | - Marta Kwapisz
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Isabelle Canal
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Duy Khanh Phung
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Laura Plassart
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Régine Capeyrou
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Yann Moalic
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Mohamed Jebbar
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Didier Flament
- Univ Brest, CNRS, Ifremer, UMR6197 Biologie et Ecologie des Ecosystèmes marins Profonds, F-29280 Plouzané, France
| | - Gwennaele Fichant
- LMGM, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Marie Bouvier
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| | - Béatrice Clouet-d'Orval
- MCD, Centre de Biologie Intégrative (CBI), CNRS, Université de Toulouse, UT3, Toulouse, France
| |
Collapse
|
3
|
Leeder WM, Geyer FK, Göringer HU. Fuzzy RNA recognition by the Trypanosoma brucei editosome. Nucleic Acids Res 2022; 50:5818-5833. [PMID: 35580050 PMCID: PMC9178004 DOI: 10.1093/nar/gkac357] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/20/2022] [Accepted: 04/26/2022] [Indexed: 11/30/2022] Open
Abstract
The assembly of high molecular mass ribonucleoprotein complexes typically relies on the binary interaction of defined RNA sequences or precisely folded RNA motifs with dedicated RNA-binding domains on the protein side. Here we describe a new molecular recognition principle of RNA molecules by a high molecular mass protein complex. By chemically probing the solvent accessibility of mitochondrial pre-mRNAs when bound to the Trypanosoma brucei editosome, we identified multiple similar but non-identical RNA motifs as editosome contact sites. However, by treating the different motifs as mathematical graph objects we demonstrate that they fit a consensus 2D-graph consisting of 4 vertices (V) and 3 edges (E) with a Laplacian eigenvalue of 0.5477 (λ2). We establish that synthetic 4V(3E)-RNAs are sufficient to compete for the editosomal pre-mRNA binding site and that they inhibit RNA editing in vitro. Furthermore, we demonstrate that only two topological indices are necessary to predict the binding of any RNA motif to the editosome with a high level of confidence. Our analysis corroborates that the editosome has adapted to the structural multiplicity of the mitochondrial mRNA folding space by recognizing a fuzzy continuum of RNA folds that fit a consensus graph descriptor.
Collapse
Affiliation(s)
| | - Felix Klaus Geyer
- Molecular Genetics, Technical University Darmstadt, 64287 Darmstadt, Germany
| | | |
Collapse
|
4
|
Mehta V, Moshiri H, Srikanth A, Kala S, Lukeš J, Salavati R. Sulfonated inhibitors of the RNA editing ligases validate the essential role of the MRP1/2 proteins in kinetoplastid RNA editing. RNA (NEW YORK, N.Y.) 2020; 26:827-835. [PMID: 32276989 PMCID: PMC7297121 DOI: 10.1261/rna.075598.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 04/06/2020] [Indexed: 05/21/2023]
Abstract
The RNA editing core complex (RECC) catalyzes mitochondrial U-insertion/deletion mRNA editing in trypanosomatid flagellates. Some naphthalene-based sulfonated compounds, such as C35 and MrB, competitively inhibit the auto-adenylylation activity of an essential RECC enzyme, kinetoplastid RNA editing ligase 1 (KREL1), required for the final step in editing. Previous studies revealed the ability of these compounds to interfere with the interaction between the editosome and its RNA substrates, consequently affecting all catalytic activities that comprise RNA editing. This observation implicates a critical function for the affected RNA binding proteins in RNA editing. In this study, using the inhibitory compounds, we analyzed the composition and editing activities of functional editosomes and identified the mitochondrial RNA binding proteins 1 and 2 (MRP1/2) as their preferred targets. While the MRP1/2 heterotetramer complex is known to bind guide RNA and promote annealing to its cognate pre-edited mRNA, its role in RNA editing remained enigmatic. We show that the compounds affect the association between the RECC and MRP1/2 heterotetramer. Furthermore, RECC purified post-treatment with these compounds exhibit compromised in vitro RNA editing activity that, remarkably, recovers upon the addition of recombinant MRP1/2 proteins. This work provides experimental evidence that the MRP1/2 heterotetramer is required for in vitro RNA editing activity and substantiates the hypothesized role of these proteins in presenting the RNA duplex to the catalytic complex in the initial steps of RNA editing.
Collapse
Affiliation(s)
- Vaibhav Mehta
- Department of Biochemistry, McGill University, Montreal, H3G1Y6 Quebec, Canada
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, H9X 3V9 Quebec, Canada
| | - Houtan Moshiri
- Department of Biochemistry, McGill University, Montreal, H3G1Y6 Quebec, Canada
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, H9X 3V9 Quebec, Canada
| | - Akshaya Srikanth
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, H9X 3V9 Quebec, Canada
| | - Smriti Kala
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, H9X 3V9 Quebec, Canada
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre and Faculty of Science, University of South Bohemia, 37005 České Budějovice (Budweis), Czech Republic
| | - Reza Salavati
- Department of Biochemistry, McGill University, Montreal, H3G1Y6 Quebec, Canada
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, H9X 3V9 Quebec, Canada
| |
Collapse
|
5
|
Janowski R, Niessing D. The large family of PC4-like domains - similar folds and functions throughout all kingdoms of life. RNA Biol 2020; 17:1228-1238. [PMID: 32476604 PMCID: PMC7549692 DOI: 10.1080/15476286.2020.1761639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RNA- and DNA-binding domains are essential building blocks for specific regulation of gene expression. While a number of canonical nucleic acid binding domains share sequence and structural conservation, others are less obviously linked by evolutionary traits. In this review, we describe a protein fold of about 150 aa in length, bearing a conserved β-β-β-β-α-linker-β-β-β-β-α topology and similar nucleic acid binding properties but no apparent sequence conservation. The same overall fold can also be achieved by dimerization of two proteins, each bearing a β-β-β-β-α topology. These proteins include but are not limited to the transcription factors PC4 and P24 from humans and plants, respectively, the human RNA-transport factor Pur-α (also termed PURA), as well as the ssDNA-binding SP_0782 protein from Streptococcus pneumonia and the bacteriophage coat proteins PP7 and MS2. Besides their common overall topology, these proteins share common nucleic acids binding surfaces and thus functional similarity. We conclude that these PC4-like domains include proteins from all kingdoms of life and are much more abundant than previously known.
Collapse
Affiliation(s)
- Robert Janowski
- Institute of Structural Biology, Helmholtz Zentrum München - German Research Center for Environmental Health , Neuherberg, Germany
| | - Dierk Niessing
- Institute of Structural Biology, Helmholtz Zentrum München - German Research Center for Environmental Health , Neuherberg, Germany.,Institute of Pharmaceutical Biotechnology, Ulm University , Ulm, Germany
| |
Collapse
|
6
|
Aphasizheva I, Alfonzo J, Carnes J, Cestari I, Cruz-Reyes J, Göringer HU, Hajduk S, Lukeš J, Madison-Antenucci S, Maslov DA, McDermott SM, Ochsenreiter T, Read LK, Salavati R, Schnaufer A, Schneider A, Simpson L, Stuart K, Yurchenko V, Zhou ZH, Zíková A, Zhang L, Zimmer S, Aphasizhev R. Lexis and Grammar of Mitochondrial RNA Processing in Trypanosomes. Trends Parasitol 2020; 36:337-355. [PMID: 32191849 PMCID: PMC7083771 DOI: 10.1016/j.pt.2020.01.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/19/2020] [Accepted: 01/22/2020] [Indexed: 12/15/2022]
Abstract
Trypanosoma brucei spp. cause African human and animal trypanosomiasis, a burden on health and economy in Africa. These hemoflagellates are distinguished by a kinetoplast nucleoid containing mitochondrial DNAs of two kinds: maxicircles encoding ribosomal RNAs (rRNAs) and proteins and minicircles bearing guide RNAs (gRNAs) for mRNA editing. All RNAs are produced by a phage-type RNA polymerase as 3' extended precursors, which undergo exonucleolytic trimming. Most pre-mRNAs proceed through 3' adenylation, uridine insertion/deletion editing, and 3' A/U-tailing. The rRNAs and gRNAs are 3' uridylated. Historically, RNA editing has attracted major research effort, and recently essential pre- and postediting processing events have been discovered. Here, we classify the key players that transform primary transcripts into mature molecules and regulate their function and turnover.
Collapse
Affiliation(s)
- Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA 02118, USA.
| | - Juan Alfonzo
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Jason Carnes
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Igor Cestari
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9, Québec, Canada
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - H Ulrich Göringer
- Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Stephen Hajduk
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Susan Madison-Antenucci
- Parasitology Laboratory, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Dmitri A Maslov
- Department of Molecular, Cell, and Systems Biology, University of California - Riverside, Riverside, CA 92521, USA
| | - Suzanne M McDermott
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Torsten Ochsenreiter
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern CH-3012, Switzerland
| | - Laurie K Read
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Reza Salavati
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9, Québec, Canada
| | - Achim Schnaufer
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern CH-3012, Switzerland
| | - Larry Simpson
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095, USA
| | - Kenneth Stuart
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Vyacheslav Yurchenko
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic; Martsinovsky Institute of Medical Parasitology, Sechenov University, Moscow, Russia
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095, USA
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Liye Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Sara Zimmer
- University of Minnesota Medical School, Duluth campus, Duluth, MN 55812, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA 02118, USA
| |
Collapse
|
7
|
Tylec BL, Simpson RM, Kirby LE, Chen R, Sun Y, Koslowsky DJ, Read LK. Intrinsic and regulated properties of minimally edited trypanosome mRNAs. Nucleic Acids Res 2019; 47:3640-3657. [PMID: 30698753 PMCID: PMC6468165 DOI: 10.1093/nar/gkz012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/02/2019] [Accepted: 01/08/2019] [Indexed: 12/17/2022] Open
Abstract
Most mitochondrial mRNAs in kinetoplastids require extensive uridine insertion/deletion editing to generate translatable open reading frames. Editing is specified by trans-acting gRNAs and involves a complex machinery including basal and accessory factors. Here, we utilize high-throughput sequencing to analyze editing progression in two minimally edited mRNAs that provide a simplified system due their requiring only two gRNAs each for complete editing. We show that CYb and MURF2 mRNAs exhibit barriers to editing progression that differ from those previously identified for pan-edited mRNAs, primarily at initial gRNA usage and gRNA exchange. We demonstrate that mis-edited junctions arise through multiple pathways including mis-alignment of cognate gRNA, incorrect and sometimes promiscuous gRNA utilization and inefficient gRNA anchoring. We then examined the roles of accessory factors RBP16 and MRP1/2 in maintaining edited CYb and MURF2 populations. RBP16 is essential for initiation of CYb and MURF2 editing, as well as MURF2 editing progression. In contrast, MRP1/2 stabilizes both edited mRNA populations, while further promoting progression of MURF2 mRNA editing. We also analyzed the effects of RNA Editing Substrate Binding Complex components, TbRGG2 and GAP1, and show that both proteins modestly impact progression of editing on minimally edited mRNAs, suggesting a novel function for GAP1.
Collapse
Affiliation(s)
- Brianna L Tylec
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203
| | - Rachel M Simpson
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203
| | - Laura E Kirby
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824
| | - Runpu Chen
- Department of Computer Science and Engineering, University at Buffalo, Buffalo, NY 14260
| | - Yijun Sun
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203
| | - Donna J Koslowsky
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824
| | - Laurie K Read
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203
| |
Collapse
|
8
|
Mesitov MV, Yu T, Suematsu T, Sement FM, Zhang L, Yu C, Huang L, Aphasizheva I. Pentatricopeptide repeat poly(A) binding protein KPAF4 stabilizes mitochondrial mRNAs in Trypanosoma brucei. Nat Commun 2019; 10:146. [PMID: 30635574 PMCID: PMC6329795 DOI: 10.1038/s41467-018-08137-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 12/19/2018] [Indexed: 01/25/2023] Open
Abstract
In Trypanosoma brucei, most mitochondrial mRNAs undergo editing, and 3′ adenylation and uridylation. The internal sequence changes and terminal extensions are coordinated: pre-editing addition of the short (A) tail protects the edited transcript against 3′-5′ degradation, while post-editing A/U-tailing renders mRNA competent for translation. Participation of a poly(A) binding protein (PABP) in coupling of editing and 3′ modification processes has been inferred, but its identity and mechanism of action remained elusive. We report identification of KPAF4, a pentatricopeptide repeat-containing PABP which sequesters the A-tail and impedes mRNA degradation. Conversely, KPAF4 inhibits uridylation of A-tailed transcripts and, therefore, premature A/U-tailing of partially-edited mRNAs. This quality check point likely prevents translation of incompletely edited mRNAs. We also find that RNA editing substrate binding complex (RESC) mediates the interaction between the 5′ end-bound pyrophosphohydrolase MERS1 and 3′ end-associated KPAF4 to enable mRNA circularization. This event appears to be critical for edited mRNA stability. Polyadenylation stabilizes edited mitochondrial mRNAs in Trypanosoma brucei, but the involved poly(A) binding protein is unknown. Here, Mesitov et al. show that a pentatricopeptide repeat factor KPAF4 binds to A-tail and prevents exonucleolytic degradation as well as translation of incompletely edited mRNAs.
Collapse
Affiliation(s)
- Mikhail V Mesitov
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, 02118, USA
| | - Tian Yu
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, 02118, USA.,Bioinformatics Program, Boston University, Boston, MA, 02215, USA
| | - Takuma Suematsu
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, 02118, USA
| | - Francois M Sement
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, 02118, USA
| | - Liye Zhang
- School of Life Science and Technology, ShanghaiTechUniversity, 201210, Shanghai, China
| | - Clinton Yu
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, 92697, USA
| | - Lan Huang
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, 92697, USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, 02118, USA.
| |
Collapse
|
9
|
Dixit S, Lukeš J. Combinatorial interplay of RNA-binding proteins tunes levels of mitochondrial mRNA in trypanosomes. RNA (NEW YORK, N.Y.) 2018; 24:1594-1606. [PMID: 30120147 PMCID: PMC6191715 DOI: 10.1261/rna.066233.118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/10/2018] [Indexed: 05/11/2023]
Abstract
MRP1/2 is a heteromeric protein complex that functions in the trypanosomatid mitochondrion as part of the RNA editing machinery, which facilitates multiple targeted insertions and deletions of uridines. MRP1/2 was shown to interact with MRB8170, which initiates RNA editing by marking pre-edited mRNAs, while TbRGG2 is required for its efficient progression on pan-edited mRNAs. Both MRP1/2 and TbRGG2 are capable of modulating RNA-RNA interactions in vitro. As determined by using iCLIP and RIP-qPCR, RNAs bound to MRP1/2 are characterized and compared with those associated with MRB8170 and TbRGG2. We provide evidence that MRP1 and MRB8170 have correlated binding and similar RNA crosslinking peak profiles over minimally and never-edited mRNAs. Our results suggest that MRP1 assists MRB8170 in RNA editing on minimally edited mRNAs.
Collapse
Affiliation(s)
- Sameer Dixit
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, 37005 České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, 37005 České Budějovice (Budweis), Czech Republic
| |
Collapse
|
10
|
Recent advances in trypanosomatid research: genome organization, expression, metabolism, taxonomy and evolution. Parasitology 2018; 146:1-27. [PMID: 29898792 DOI: 10.1017/s0031182018000951] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Unicellular flagellates of the family Trypanosomatidae are obligatory parasites of invertebrates, vertebrates and plants. Dixenous species are aetiological agents of a number of diseases in humans, domestic animals and plants. Their monoxenous relatives are restricted to insects. Because of the high biological diversity, adaptability to dramatically different environmental conditions, and omnipresence, these protists have major impact on all biotic communities that still needs to be fully elucidated. In addition, as these organisms represent a highly divergent evolutionary lineage, they are strikingly different from the common 'model system' eukaryotes, such as some mammals, plants or fungi. A number of excellent reviews, published over the past decade, were dedicated to specialized topics from the areas of trypanosomatid molecular and cell biology, biochemistry, host-parasite relationships or other aspects of these fascinating organisms. However, there is a need for a more comprehensive review that summarizing recent advances in the studies of trypanosomatids in the last 30 years, a task, which we tried to accomplish with the current paper.
Collapse
|
11
|
Suematsu T, Zhang L, Aphasizheva I, Monti S, Huang L, Wang Q, Costello CE, Aphasizhev R. Antisense Transcripts Delimit Exonucleolytic Activity of the Mitochondrial 3' Processome to Generate Guide RNAs. Mol Cell 2016; 61:364-378. [PMID: 26833087 PMCID: PMC4744118 DOI: 10.1016/j.molcel.2016.01.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/16/2015] [Accepted: 12/24/2015] [Indexed: 12/21/2022]
Abstract
Small, noncoding RNA biogenesis typically involves cleavage of structured precursor by RNase III-like endonucleases. However, guide RNAs (gRNAs) that direct U-insertion/deletion mRNA editing in mitochondria of trypanosomes maintain 5' triphosphate characteristic of the transcription initiation and possess a U-tail indicative of 3' processing and uridylation. Here, we identified a protein complex composed of RET1 TUTase, DSS1 3'-5' exonuclease, and three additional subunits. This complex, termed mitochondrial 3' processome (MPsome), is responsible for primary uridylation of ∼800 nt gRNA precursors, their processive degradation to a mature size of 40-60 nt, and secondary U-tail addition. Both strands of the gRNA gene are transcribed into sense and antisense precursors of similar lengths. Head-to-head hybridization of these transcripts blocks symmetrical 3'-5' degradation at a fixed distance from the double-stranded region. Together, our findings suggest a model in which gRNA is derived from the 5' extremity of a primary molecule by uridylation-induced, antisense transcription-controlled 3'-5' exonucleolytic degradation.
Collapse
Affiliation(s)
- Takuma Suematsu
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, USA
| | - Liye Zhang
- Section of Computational Biomedicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, USA
| | - Stefano Monti
- Section of Computational Biomedicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Lan Huang
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA
| | - Qi Wang
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Catherine E Costello
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, USA; Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
| |
Collapse
|
12
|
Aphasizheva I, Aphasizhev R. U-Insertion/Deletion mRNA-Editing Holoenzyme: Definition in Sight. Trends Parasitol 2015; 32:144-156. [PMID: 26572691 DOI: 10.1016/j.pt.2015.10.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 10/06/2015] [Accepted: 10/12/2015] [Indexed: 11/16/2022]
Abstract
RNA editing is a process that alters DNA-encoded sequences and is distinct from splicing, 5' capping, and 3' additions. In 30 years since editing was discovered in mitochondria of trypanosomes, several functionally and evolutionarily unrelated mechanisms have been described in eukaryotes, archaea, and viruses. Editing events are predominantly post-transcriptional and include nucleoside insertions and deletions, and base substitutions and modifications. Here, we review the mechanism of uridine insertion/deletion mRNA editing in kinetoplastid protists typified by Trypanosoma brucei. This type of editing corrects frameshifts, introduces translation punctuation signals, and often adds hundreds of uridines to create protein-coding sequences. We focus on protein complexes responsible for editing reactions and their interactions with other elements of the mitochondrial gene expression pathway.
Collapse
Affiliation(s)
- Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, USA.
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA 02118, USA; Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
| |
Collapse
|
13
|
Verner Z, Basu S, Benz C, Dixit S, Dobáková E, Faktorová D, Hashimi H, Horáková E, Huang Z, Paris Z, Peña-Diaz P, Ridlon L, Týč J, Wildridge D, Zíková A, Lukeš J. Malleable mitochondrion of Trypanosoma brucei. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:73-151. [PMID: 25708462 DOI: 10.1016/bs.ircmb.2014.11.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The importance of mitochondria for a typical aerobic eukaryotic cell is undeniable, as the list of necessary mitochondrial processes is steadily growing. Here, we summarize the current knowledge of mitochondrial biology of an early-branching parasitic protist, Trypanosoma brucei, a causative agent of serious human and cattle diseases. We present a comprehensive survey of its mitochondrial pathways including kinetoplast DNA replication and maintenance, gene expression, protein and metabolite import, major metabolic pathways, Fe-S cluster synthesis, ion homeostasis, organellar dynamics, and other processes. As we describe in this chapter, the single mitochondrion of T. brucei is everything but simple and as such rivals mitochondria of multicellular organisms.
Collapse
Affiliation(s)
- Zdeněk Verner
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia; Present address: Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Somsuvro Basu
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Germany
| | - Corinna Benz
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Sameer Dixit
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Dobáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Drahomíra Faktorová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Horáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Zhenqiu Huang
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Zdeněk Paris
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Priscila Peña-Diaz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Lucie Ridlon
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Salk Institute, La Jolla, San Diego, USA
| | - Jiří Týč
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - David Wildridge
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| |
Collapse
|
14
|
Dynamics of mitochondrial RNA-binding protein complex in Trypanosoma brucei and its petite mutant under optimized immobilization conditions. EUKARYOTIC CELL 2014; 13:1232-40. [PMID: 25063375 DOI: 10.1128/ec.00149-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
There are a variety of complex metabolic processes ongoing simultaneously in the single, large mitochondrion of Trypanosoma brucei. Understanding the organellar environment and dynamics of mitochondrial proteins requires quantitative measurement in vivo. In this study, we have validated a method for immobilizing both procyclic stage (PS) and bloodstream stage (BS) T. brucei brucei with a high level of cell viability over several hours and verified its suitability for undertaking fluorescence recovery after photobleaching (FRAP), with mitochondrion-targeted yellow fluorescent protein (YFP). Next, we used this method for comparative analysis of the translational diffusion of mitochondrial RNA-binding protein 1 (MRP1) in the BS and in T. b. evansi. The latter flagellate is like petite mutant Saccharomyces cerevisiae because it lacks organelle-encoded nucleic acids. FRAP measurement of YFP-tagged MRP1 in both cell lines illuminated from a new perspective how the absence or presence of RNA affects proteins involved in mitochondrial RNA metabolism. This work represents the first attempt to examine this process in live trypanosomes.
Collapse
|
15
|
Aphasizhev R, Aphasizheva I. Mitochondrial RNA editing in trypanosomes: small RNAs in control. Biochimie 2014; 100:125-31. [PMID: 24440637 PMCID: PMC4737708 DOI: 10.1016/j.biochi.2014.01.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/06/2014] [Indexed: 12/29/2022]
Abstract
Mitochondrial mRNA editing in trypanosomes is a posttranscriptional processing pathway thereby uridine residues (Us) are inserted into, or deleted from, messenger RNA precursors. By correcting frameshifts, introducing start and stop codons, and often adding most of the coding sequence, editing restores open reading frames for mitochondrially-encoded mRNAs. There can be hundreds of editing events in a single pre-mRNA, typically spaced by few nucleotides, with U-insertions outnumbering U-deletions by approximately 10-fold. The mitochondrial genome is composed of ∼50 maxicircles and thousands of minicircles. Catenated maxi- and minicircles are packed into a dense structure called the kinetoplast; maxicircles yield rRNA and mRNA precursors while guide RNAs (gRNAs) are produced predominantly from minicircles, although varying numbers of maxicircle-encoded gRNAs have been identified in kinetoplastids species. Guide RNAs specify positions and the numbers of inserted or deleted Us by hybridizing to pre-mRNA and forming series of mismatches. These 50-60 nucleotide (nt) molecules are 3' uridylated by RET1 TUTase and stabilized via association with the gRNA binding complex (GRBC). Editing reactions of mRNA cleavage, U-insertion or deletion, and ligation are catalyzed by the RNA editing core complex (RECC). To function in mitochondrial translation, pre-mRNAs must further undergo post-editing 3' modification by polyadenylation/uridylation. Recent studies revealed a highly compound nature of mRNA editing and polyadenylation complexes and their interactions with the translational machinery. Here we focus on mechanisms of RNA editing and its functional coupling with pre- and post-editing 3' mRNA modification and gRNA maturation pathways.
Collapse
Affiliation(s)
- Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, 72 East Concord Street, Evans 4th Floor, E426, Boston, MA 02118, USA.
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, 72 East Concord Street, Evans 4th Floor, E426, Boston, MA 02118, USA
| |
Collapse
|
16
|
Abstract
RNA editing describes a chemically diverse set of biomolecular reactions in which the nucleotide sequence of RNA molecules is altered. Editing reactions have been identified in many organisms and frequently contribute to the maturation of organellar transcripts. A special editing reaction has evolved within the mitochondria of the kinetoplastid protozoa. The process is characterized by the insertion and deletion of uridine nucleotides into otherwise nontranslatable messenger RNAs. Kinetoplastid RNA editing involves an exclusive class of small, noncoding RNAs known as guide RNAs. Furthermore, a unique molecular machinery, the editosome, catalyzes the process. Editosomes are megadalton multienzyme assemblies that provide a catalytic surface for the individual steps of the reaction cycle. Here I review the current mechanistic understanding and molecular inventory of kinetoplastid RNA editing and the editosome machinery. Special emphasis is placed on the molecular morphology of the editing complex in order to correlate structural features with functional characteristics.
Collapse
Affiliation(s)
- H Ulrich Göringer
- Department of Genetics, Darmstadt University of Technology, Germany.
| |
Collapse
|
17
|
Böhm C, Katari VS, Brecht M, Göringer HU. Trypanosoma brucei 20 S editosomes have one RNA substrate-binding site and execute RNA unwinding activity. J Biol Chem 2012; 287:26268-77. [PMID: 22661715 PMCID: PMC3406711 DOI: 10.1074/jbc.m112.365916] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/10/2012] [Indexed: 12/30/2022] Open
Abstract
Editing of mitochondrial pre-mRNAs in African trypanosomes generates full-length transcripts by the site-specific insertion and deletion of uridylate nucleotides. The reaction is catalyzed by a 0.8 MDa multienzyme complex, the editosome. Although the binding of substrate pre-edited mRNAs and cognate guide RNAs (gRNAs) represents the first step in the reaction cycle, the biochemical and biophysical details of the editosome/RNA interaction are not understood. Here we show that editosomes bind full-length substrate mRNAs with nanomolar affinity in a nonselective fashion. The complexes do not discriminate-neither kinetically nor thermodynamically-between different mitochondrial pre-mRNAs or between edited and unedited versions of the same transcript. They also bind gRNAs and gRNA/pre-mRNA hybrid RNAs with similar affinities and association rate constants. Gold labeling of editosome-bound RNA in combination with transmission electron microscopy identified a single RNA-binding site per editosome. However, atomic force microscopy of individual pre-mRNA-editosome complexes revealed that multiple editosomes can interact with one pre-mRNA. Lastly, we demonstrate a so far unknown activity of the editing machinery: editosome-bound RNA becomes unfolded by a chaperone-type RNA unwinding activity.
Collapse
MESH Headings
- Binding Sites
- Macromolecular Substances/chemistry
- Macromolecular Substances/ultrastructure
- Microscopy, Atomic Force
- Microscopy, Electron, Transmission
- Nucleic Acid Conformation
- Protein Binding
- Protozoan Proteins/chemistry
- Protozoan Proteins/ultrastructure
- RNA Processing, Post-Transcriptional
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/ultrastructure
- RNA, Messenger/chemistry
- RNA, Messenger/ultrastructure
- RNA, Mitochondrial
- RNA, Protozoan/chemistry
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/ultrastructure
- Surface Plasmon Resonance
- Trypanosoma brucei brucei/enzymology
Collapse
Affiliation(s)
- Cordula Böhm
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Venkata Subbaraju Katari
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Michael Brecht
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - H. Ulrich Göringer
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| |
Collapse
|
18
|
Multifunctional G-rich and RRM-containing domains of TbRGG2 perform separate yet essential functions in trypanosome RNA editing. EUKARYOTIC CELL 2012; 11:1119-31. [PMID: 22798390 DOI: 10.1128/ec.00175-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Efficient editing of Trypanosoma brucei mitochondrial RNAs involves the actions of multiple accessory factors. T. brucei RGG2 (TbRGG2) is an essential protein crucial for initiation and 3'-to-5' progression of editing. TbRGG2 comprises an N-terminal G-rich region containing GWG and RG repeats and a C-terminal RNA recognition motif (RRM)-containing domain. Here, we perform in vitro and in vivo separation-of-function studies to interrogate the mechanism of TbRGG2 action in RNA editing. TbRGG2 preferentially binds preedited mRNA in vitro with high affinity attributable to its G-rich region. RNA-annealing and -melting activities are separable, carried out primarily by the G-rich and RRM domains, respectively. In vivo, the G-rich domain partially complements TbRGG2 knockdown, but the RRM domain is also required. Notably, TbRGG2's RNA-melting activity is dispensable for RNA editing in vivo. Interactions between TbRGG2 and MRB1 complex proteins are mediated by both G-rich and RRM-containing domains, depending on the binding partner. Overall, our results are consistent with a model in which the high-affinity RNA binding and RNA-annealing activities of the G-rich domain are essential for RNA editing in vivo. The RRM domain may have key functions involving interactions with the MRB1 complex and/or regulation of the activities of the G-rich domain.
Collapse
|
19
|
|
20
|
Aphasizhev R, Aphasizheva I. Uridine insertion/deletion editing in trypanosomes: a playground for RNA-guided information transfer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2011; 2:669-85. [PMID: 21823228 PMCID: PMC3154072 DOI: 10.1002/wrna.82] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RNA editing is a collective term referring to enzymatic processes that change RNA sequence apart from splicing, 5' capping or 3' extension. In this article, we focus on uridine insertion/deletion mRNA editing found exclusively in mitochondria of kinetoplastid protists. This type of editing corrects frameshifts, introduces start and stops codons, and often adds much of the coding sequence to create an open reading frame. The mitochondrial genome of trypanosomatids, the most extensively studied clade within the order Kinetoplastida, is composed of ∼50 maxicircles with limited coding capacity and thousands of minicircles. To produce functional mRNAs, a multitude of nuclear-encoded factors mediate interactions of maxicircle-encoded pre-mRNAs with a vast repertoire of minicircle-encoded guide RNAs. Editing reactions of mRNA cleavage, U-insertions or U-deletions, and ligation are catalyzed by the RNA editing core complex (RECC, the 20S editosome) while each step of this enzymatic cascade is directed by guide RNAs. These 50-60 nucleotide (nt) molecules are 3' uridylated by RET1 TUTase and stabilized via association with the gRNA binding complex (GRBC). Remarkably, the information transfer between maxicircle and minicircle transcriptomes does not rely on template-dependent polymerization of nucleic acids. Instead, intrinsic substrate specificities of key enzymes are largely responsible for the fidelity of editing. Conversely, the efficiency of editing is enhanced by assembling enzymes and RNA binding proteins into stable multiprotein complexes. WIREs RNA 2011 2 669-685 DOI: 10.1002/wrna.82 For further resources related to this article, please visit the WIREs website.
Collapse
MESH Headings
- Endonucleases/chemistry
- Endonucleases/genetics
- Endonucleases/metabolism
- Models, Biological
- Models, Molecular
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA Editing/genetics
- RNA Editing/physiology
- RNA Helicases/chemistry
- RNA Helicases/genetics
- RNA Helicases/metabolism
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/chemistry
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Trypanosoma/genetics
- Trypanosoma/metabolism
- Uridine/chemistry
Collapse
Affiliation(s)
- Ruslan Aphasizhev
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, USA.
| | | |
Collapse
|
21
|
Göringer HU, Katari VS, Böhm C. The structural landscape of native editosomes in African trypanosomes. WILEY INTERDISCIPLINARY REVIEWS. RNA 2011; 2:395-407. [PMID: 21957025 DOI: 10.1002/wrna.67] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The majority of mitochondrial pre-messenger RNAs in African trypanosomes are substrates of a U-nucleotide-specific insertion/deletion-type RNA editing reaction. The process converts nonfunctional pre-mRNAs into translation-competent molecules and can generate protein diversity by alternative editing. High molecular mass protein complexes termed editosomes catalyze the processing reaction. They stably interact with pre-edited mRNAs and small noncoding RNAs, known as guide RNAs (gRNAs), which act as templates in the reaction. Editosomes provide a molecular surface for the individual steps of the catalytic reaction cycle and although the protein inventory of the complexes has been studied in detail, a structural analysis of the processing machinery has only recently been accomplished. Electron microscopy in combination with single particle reconstruction techniques has shown that steady state isolates of editosomes contain ensembles of two classes of stable complexes with calculated apparent hydrodynamic sizes of 20S and 35-40S. 20S editosomes are free of substrate RNAs, whereas 35-40S editosomes are associated with endogenous mRNA and gRNA molecules. Both complexes are characterized by a diverse structural landscape, which include complexes that lack or possess defined subdomains. Here, we summarize the consensus models and structural landmarks of both complexes. We correlate structural features with functional characteristics and provide an outlook into dynamic aspects of the editing reaction cycle.
Collapse
Affiliation(s)
- H Ulrich Göringer
- Department of Microbiology and Genetics, Darmstadt University of Technology, Darmstadt, Germany.
| | | | | |
Collapse
|
22
|
Abstract
The RNA folding trajectory features numerous off-pathway folding traps, which represent conformations that are often equally as stable as the native functional ones. Therefore, the conversion between these off-pathway structures and the native correctly folded ones is the critical step in RNA folding. This process, referred to as RNA refolding, is slow, and is represented by a transition state that has a characteristic high free energy. Because this kinetically limiting process occurs in vivo, proteins (called RNA chaperones) have evolved that facilitate the (re)folding of RNA molecules. Here, we present an overview of how proteins interact with RNA molecules in order to achieve properly folded states. In this respect, the discrimination between static and transient interactions is crucial, as different proteins have evolved a multitude of mechanisms for RNA remodeling. For RNA chaperones that act in a sequence-unspecific manner and without the use of external sources of energy, such as ATP, transient RNA–protein interactions represent the basis of the mode of action. By presenting stretches of positively charged amino acids that are positioned in defined spatial configurations, RNA chaperones enable the RNA backbone, via transient electrostatic interactions, to sample a wider conformational space that opens the route for efficient refolding reactions.
Collapse
Affiliation(s)
- Martina Doetsch
- Department of Biochemistry and Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | | | | |
Collapse
|
23
|
Doetsch M, Fürtig B, Gstrein T, Stampfl S, Schroeder R. The RNA annealing mechanism of the HIV-1 Tat peptide: conversion of the RNA into an annealing-competent conformation. Nucleic Acids Res 2011; 39:4405-18. [PMID: 21297117 PMCID: PMC3105384 DOI: 10.1093/nar/gkq1339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The annealing of nucleic acids to (partly) complementary RNA or DNA strands is involved in important cellular processes. A variety of proteins have been shown to accelerate RNA/RNA annealing but their mode of action is still mainly uncertain. In order to study the mechanism of protein-facilitated acceleration of annealing we selected a short peptide, HIV-1 Tat(44–61), which accelerates the reaction efficiently. The activity of the peptide is strongly regulated by mono- and divalent cations which hints at the importance of electrostatic interactions between RNA and peptide. Mutagenesis of the peptide illustrated the dominant role of positively charged amino acids in RNA annealing—both the overall charge of the molecule and a precise distribution of basic amino acids within the peptide are important. Additionally, we found that Tat(44–61) drives the RNA annealing reaction via entropic rather than enthalpic terms. One-dimensional-NMR data suggest that the peptide changes the population distribution of possible RNA structures to favor an annealing-prone RNA conformation, thereby increasing the fraction of colliding RNA molecules that successfully anneal.
Collapse
Affiliation(s)
- Martina Doetsch
- Max F Perutz Laboratories, Dr Bohrgasse 9/5, 1030 Vienna, Austria
| | | | | | | | | |
Collapse
|
24
|
Doetsch M, Gstrein T, Schroeder R, Fürtig B. Mechanisms of StpA-mediated RNA remodeling. RNA Biol 2010; 7:735-43. [PMID: 21057189 DOI: 10.4161/rna.7.6.13882] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In bacteria, transcription, translation and gene regulation are highly coupled processes. The achievement of a certain functional structure at a distinct temporal and spatial position is therefore essential for RNA molecules. Proteins that facilitate this proper folding of RNA molecules are called RNA chaperones. Here a prominent example from E. coli is reviewed: the nucleoid associated protein StpA. Based on its various RNA remodeling functions, we propose a mechanistic model that explains how StpA promotes RNA folding. Through transient interactions via the RNA backbone, thereby shielding repelling charges in RNA, it pre-positions the RNA molecules for the successful formation of transition states from encounter complexes.
Collapse
|
25
|
Ammerman ML, Presnyak V, Fisk JC, Foda BM, Read LK. TbRGG2 facilitates kinetoplastid RNA editing initiation and progression past intrinsic pause sites. RNA (NEW YORK, N.Y.) 2010; 16:2239-51. [PMID: 20855539 PMCID: PMC2957062 DOI: 10.1261/rna.2285510] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 08/09/2010] [Indexed: 05/20/2023]
Abstract
TbRGG2 is an essential kinetoplastid RNA editing accessory factor that acts specifically on pan-edited RNAs. To understand the mechanism of TbRGG2 action, we undertook an in-depth analysis of edited RNA populations in TbRGG2 knockdown cells and an in vitro examination of the biochemical activities of the protein. We demonstrate that TbRGG2 down-regulation more severely impacts editing at the 5' ends of pan-edited RNAs than at their 3' ends. The initiation of editing is reduced to some extent in TbRGG2 knockdown cells. In addition, TbRGG2 plays a post-initiation role as editing becomes stalled in TbRGG2-depleted cells, resulting in an overall decrease in the 3' to 5' progression of editing. Detailed analyses of edited RNAs from wild-type and TbRGG2-depleted cells reveal that TbRGG2 facilitates progression of editing past intrinsic pause sites that often correspond to the 3' ends of cognate guide RNAs (gRNAs). In addition, noncanonically edited junction regions are either absent or significantly shortened in TbRGG2-depleted cells, consistent with impaired gRNA transitions. Sequence analysis further suggests that TbRGG2 facilitates complete utilization of certain gRNAs. In vitro RNA annealing and in vivo RNA unwinding assays demonstrate that TbRGG2 can modulate RNA-RNA interactions. Collectively, these data are consistent with a model in which TbRGG2 facilitates initiation and 3' to 5' progression of editing through its ability to affect gRNA utilization, both during the transition between specific gRNAs and during usage of certain gRNAs.
Collapse
Affiliation(s)
- Michelle L Ammerman
- Department of Microbiology and Immunology, University at Buffalo School of Medicine, Buffalo, New York 14214, USA
| | | | | | | | | |
Collapse
|
26
|
Kala S, Salavati R. OB-fold domain of KREPA4 mediates high-affinity interaction with guide RNA and possesses annealing activity. RNA (NEW YORK, N.Y.) 2010; 16:1951-67. [PMID: 20713467 PMCID: PMC2941104 DOI: 10.1261/rna.2124610] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 07/19/2010] [Indexed: 05/29/2023]
Abstract
KREPA4, also called MP24, is an essential mitochondrial guide RNA (gRNA)-binding protein with a preference for the 3' oligo(U) tail in trypanosomes. Structural prediction and compositional analysis of KREPA4 have identified a conserved OB (oligonucleotide/oligosaccharide-binding)-fold at the C-terminal end and two low compositional complexity regions (LCRs) at its N terminus. Concurrent with these predictions, one or both of these regions in KREPA4 protein may be involved in gRNA binding. To test this possibility, deletion mutants of KREPA4 were made and the effects on the gRNA-binding affinities were measured by quantitative electrophoretic mobility shift assays. The gRNA-binding specificities of these mutants were evaluated by competition experiments using gRNAs with U-tail deletions or stem-loop modifications and uridylated nonguide RNAs or heterologous RNA. Our results identified the predicted OB-fold as the functional domain of KREPA4 that mediates a high-affinity interaction with the gRNA oligo(U) tail. An additional contribution toward RNA-binding function was localized to LCRs that further stabilize the binding through sequence-specific interactions with the guide secondary structure. In this study we also found that the predicted OB-fold has an RNA annealing activity, representing the first report of such activity for a core component of the RNA editing complex.
Collapse
MESH Headings
- Amino Acid Sequence
- Base Sequence
- Binding, Competitive
- Kinetics
- Models, Biological
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Folding
- Protein Structure, Tertiary
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA Editing
- RNA Precursors/chemistry
- RNA Precursors/genetics
- RNA Precursors/metabolism
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA, Protozoan/chemistry
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sequence Deletion
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/metabolism
Collapse
Affiliation(s)
- Smriti Kala
- Institute of Parasitology, McGill University, Ste. Anne de Bellevue, Quebec, Canada
| | | |
Collapse
|
27
|
Reifur L, Yu LE, Cruz-Reyes J, vanHartesvelt M, Koslowsky DJ. The impact of mRNA structure on guide RNA targeting in kinetoplastid RNA editing. PLoS One 2010; 5:e12235. [PMID: 20808932 PMCID: PMC2923197 DOI: 10.1371/journal.pone.0012235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 07/23/2010] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial mRNA editing in Trypanosoma brucei requires the specific interaction of a guide RNA with its cognate mRNA. Hundreds of gRNAs are involved in the editing process, each needing to target their specific editing domain within the target message. We hypothesized that the structure surrounding the mRNA target may be a limiting factor and involved in the regulation process. In this study, we selected four mRNAs with distinct target structures and investigated how sequence and structure affected efficient gRNA targeting. Two of the mRNAs, including the ATPase subunit 6 and ND7-550 (5' end of NADH dehydrogenase subunit 7) that have open, accessible anchor binding sites show very efficient gRNA targeting. Electrophoretic mobility shift assays indicate that the cognate gRNA for ND7-550 had 10-fold higher affinity for its mRNA than the A6 pair. Surface plasmon resonance studies indicate that the difference in affinity was due to a four-fold faster association rate. As expected, mRNAs with considerable structure surrounding the anchor binding sites were less accessible and had very low affinity for their cognate gRNAs. In vitro editing assays indicate that efficient pairing is crucial for gRNA directed cleavage. However, only the A6 substrate showed gRNA-directed cleavage at the correct editing site. This suggests that different gRNA/mRNA pairs may require different "sets" of accessory factors for efficient editing. By characterizing a number of different gRNA/mRNA interactions, we may be able to define a "bank" of RNA editing substrates with different putative chaperone and other co-factor requirements. This will allow the more efficient identification and characterization of transcript specific RNA editing accessory proteins.
Collapse
Affiliation(s)
- Larissa Reifur
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Laura E. Yu
- Cell and Molecular Biology Program, College of Natural Sciences, Michigan State University, East Lansing, Michigan, United States of America
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Michelle vanHartesvelt
- Dow Corning, Teachers for a New Era, Michigan State University, East Lansing, Michigan, United States of America
| | - Donna J. Koslowsky
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, United States of America
- Cell and Molecular Biology Program, College of Natural Sciences, Michigan State University, East Lansing, Michigan, United States of America
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| |
Collapse
|
28
|
Aphasizheva I, Aphasizhev R. RET1-catalyzed uridylylation shapes the mitochondrial transcriptome in Trypanosoma brucei. Mol Cell Biol 2010; 30:1555-67. [PMID: 20086102 PMCID: PMC2832499 DOI: 10.1128/mcb.01281-09] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 10/30/2009] [Accepted: 01/05/2010] [Indexed: 01/25/2023] Open
Abstract
RNA uridylylation is critical for the expression of the mitochondrial genome in trypanosomes. Short U tails are added to guide RNAs and rRNAs, while long A/U heteropolymers mark 3' ends of most mRNAs. Three divergent mitochondrial terminal uridylyl transferases (TUTases) are known: RET1 catalyzes guide RNA (gRNA) uridylylation, RET2 executes U insertion mRNA editing, and MEAT1 associates with the editosome-like complex. However, the activities responsible for 3' uridylylation of rRNAs and mRNAs, and the roles of these modifications, are unclear. To dissect the functions of mitochondrial TUTases, we investigated the effects of their repression and overexpression on abundance, processing, 3'-end status, and in vivo stability of major mitochondrially encoded RNA classes. We show that RET1 adds U tails to gRNAs, rRNAs, and select mRNAs and contributes U's into A/U heteropolymers. Furthermore, RET1's TUTase activity is required for the nucleolytic processing of gRNA, rRNA, and mRNA precursors. The U tail's presence does not affect the stability of gRNAs and rRNAs, while transcript-specific uridylylation triggers 3' to 5' mRNA decay. We propose that the minicircle-encoded antisense transcripts, which are stabilized by RET1-catalyzed uridylylation, may direct a nucleolytic cleavage of multicistronic precursors.
Collapse
Affiliation(s)
- Inna Aphasizheva
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, California 92697
| | - Ruslan Aphasizhev
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, California 92697
| |
Collapse
|
29
|
Hernandez A, Madina BR, Ro K, Wohlschlegel JA, Willard B, Kinter MT, Cruz-Reyes J. REH2 RNA helicase in kinetoplastid mitochondria: ribonucleoprotein complexes and essential motifs for unwinding and guide RNA (gRNA) binding. J Biol Chem 2010; 285:1220-8. [PMID: 19850921 PMCID: PMC2801250 DOI: 10.1074/jbc.m109.051862] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 09/25/2009] [Indexed: 01/01/2023] Open
Abstract
Regulation of gene expression in kinetoplastid mitochondria is largely post-transcriptional and involves the orchestration of polycistronic RNA processing, 3'-terminal maturation, RNA editing, turnover, and translation; however, these processes remain poorly studied. Core editing complexes and their U-insertion/deletion activities are relatively well characterized, and a battery of ancillary factors has recently emerged. This study characterized a novel DExH-box RNA helicase, termed here REH2 (RNA editing associated helicase 2), in unique ribonucleoprotein complexes that exhibit unwinding and guide RNA binding activities, both of which required a double-stranded RNA-binding domain (dsRBD) and a functional helicase motif I of REH2. REH2 complexes and recently identified related particles share a multiprotein core but are distinguished by several differential polypeptides. Finally, REH2 associates transiently, via RNA, with editing complexes, mitochondrial ribosomes, and several ancillary factors that control editing and RNA stability. We propose that these putative higher order structures coordinate mitochondrial gene expression.
Collapse
Affiliation(s)
- Alfredo Hernandez
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Bhaskara Reddy Madina
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| | - Kevin Ro
- the Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, California 90095-1737, and
| | - James A. Wohlschlegel
- the Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, California 90095-1737, and
| | - Belinda Willard
- the Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Mike T. Kinter
- the Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Jorge Cruz-Reyes
- From the Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843
| |
Collapse
|
30
|
Graebsch A, Roche S, Niessing D. X-ray structure of Pur-alpha reveals a Whirly-like fold and an unusual nucleic-acid binding surface. Proc Natl Acad Sci U S A 2009; 106:18521-6. [PMID: 19846792 PMCID: PMC2765457 DOI: 10.1073/pnas.0907990106] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2009] [Indexed: 01/23/2023] Open
Abstract
The PUR protein family is a distinct and highly conserved class that is characterized by its sequence-specific RNA- and DNA-binding. Its best-studied family member, Pur-alpha, acts as a transcriptional regulator, as host factor for viral replication, and as cofactor for mRNP localization in dendrites. Pur-alpha-deficient mice show severe neurologic defects and die after birth. Nucleic-acid binding by Pur-alpha is mediated by its central core region, for which no structural information is available. We determined the x-ray structure of residues 40 to 185 from Drosophila melanogaster Pur-alpha, which constitutes a major part of the core region. We found that this region contains two almost identical structural motifs, termed "PUR repeats," which interact with each other to form a PUR domain. DNA- and RNA-binding studies confirmed that PUR domains are indeed functional nucleic-acid binding domains. Database analysis show that PUR domains share a fold with the Whirly class of nucleic-acid binding proteins. Structural analysis combined with mutational studies suggest that a PUR domain binds nucleic acids through two independent surface regions involving concave beta-sheets. Structure-based sequence alignment revealed that the core region harbors a third PUR repeat at its C terminus. Subsequent characterization by small-angle x-ray scattering (SAXS) and size-exclusion chromatography indicated that PUR repeat III mediates dimerization of Pur-alpha. Surface envelopes calculated from SAXS data show that the Pur-alpha dimer consisting of repeats I to III is arranged in a Z-like shape. This unexpected domain organization of the entire core domain of Pur-alpha has direct implications for ssDNA/ssRNA and dsDNA binding.
Collapse
Affiliation(s)
- Almut Graebsch
- Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Marchionini-Strasse 25, Munich, 81377, Germany; and
- Department of Chemistry and Biochemistry, Gene Center Munich and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich, 81377, Germany
| | - Stéphane Roche
- Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Marchionini-Strasse 25, Munich, 81377, Germany; and
- Department of Chemistry and Biochemistry, Gene Center Munich and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich, 81377, Germany
| | - Dierk Niessing
- Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Marchionini-Strasse 25, Munich, 81377, Germany; and
- Department of Chemistry and Biochemistry, Gene Center Munich and Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-University Munich, Feodor-Lynen-Strasse 25, Munich, 81377, Germany
| |
Collapse
|
31
|
Fisk JC, Presnyak V, Ammerman ML, Read LK. Distinct and overlapping functions of MRP1/2 and RBP16 in mitochondrial RNA metabolism. Mol Cell Biol 2009; 29:5214-25. [PMID: 19620277 PMCID: PMC2747978 DOI: 10.1128/mcb.00520-09] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 05/29/2009] [Accepted: 07/14/2009] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial RNA metabolism in Trypanosoma brucei is a complex process involving both extensive RNA editing and control of RNA stability. MRP1/2 and RBP16 are two factors that have been implicated in regulating the editing and stability of specific mRNAs. These two factors exhibit similar nonspecific RNA binding and RNA-annealing activities, suggesting that some of their actions may have been previously masked by functional redundancy. Here, we examine the functional interaction of MRP1/2 and RBP16 by separate and simultaneous RNA interference and by overexpressing RBP16 in an MRP1/2-depleted background. Simultaneous depletion of these factors resulted in synthetic lethality in procyclic trypanosomes. Analysis of mitochondrial RNAs in procyclic cells revealed distinct functions for MRP1/2 and RBP16 toward edited apocytochrome b mRNA, redundant functions in stabilization of edited ATPase subunit 6 and cytochrome oxidase subunit 3 mRNAs, and concentration-dependent positive and negative functions for RBP16 toward edited RPS12 mRNAs. While simultaneous MRP1/2-RBP16 depletion had no effect on the growth of bloodstream form cells, massive adverse effects on the levels of almost all mitochondrial RNAs were observed. These studies greatly expand our knowledge regarding the functions of MRP1/2 and RBP16 and suggest that both RNA-specific and life cycle stage-specific factors impact MRP1/2 and RBP16 functions.
Collapse
Affiliation(s)
- John C Fisk
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214.
| | | | | | | |
Collapse
|
32
|
Osato D, Rogers K, Guo Q, Li F, Richmond G, Klug F, Simpson L. Uridine insertion/deletion RNA editing in trypanosomatid mitochondria: In search of the editosome. RNA (NEW YORK, N.Y.) 2009; 15:1338-44. [PMID: 19447916 PMCID: PMC2704074 DOI: 10.1261/rna.1642809] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The RNA ligase-containing or L-complex is the core complex involved in uridine insertion/deletion RNA editing in trypanosome mitochondria. Blue native gels of glycerol gradient-separated fractions of mitochondrial lysate from cells transfected with the TAP-tagged editing protein, LC-8 (TbMP44/KREPB5), show a approximately 1 MDa L-complex band and, in addition, two minor higher molecular weight REL1-containing complexes: one (L*a) co-sedimenting with the L-complex and running in the gel at around 1.2 MDa; the other (L*b) showing a continuous increase in molecular weight from 1 MDa to particles sedimenting over 70S. The L*b-complexes appear to be mainly composed of L-complex components, since polypeptide profiles of L- and L*b-complex gradient fractions were similar in composition and L*b-complex bands often degraded to L-complex bands after manipulation or freeze-thaw cycles. The L*a-complex may be artifactual since this gel shift can be produced by various experimental manipulations. However, the nature of the change and any cellular role remain to be determined. The L*b-complexes from both lysate and TAP pull-down were sensitive to RNase A digestion, suggesting that RNA is involved with the stability of the L*b-complexes. The MRP1/2 RNA binding complex is localized mainly in the L*b-complexes in substoichiometric amounts and this association is RNase sensitive. We suggest that the L*b-complexes may provide a scaffold for dynamic interaction with other editing factors during the editing process to form the active holoenzyme or "editosome."
Collapse
Affiliation(s)
- Daren Osato
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA
| | | | | | | | | | | | | |
Collapse
|
33
|
Hashimi H, Cicová Z, Novotná L, Wen YZ, Lukes J. Kinetoplastid guide RNA biogenesis is dependent on subunits of the mitochondrial RNA binding complex 1 and mitochondrial RNA polymerase. RNA (NEW YORK, N.Y.) 2009; 15:588-99. [PMID: 19228586 PMCID: PMC2661843 DOI: 10.1261/rna.1411809] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Accepted: 01/09/2009] [Indexed: 05/20/2023]
Abstract
The mitochondrial RNA binding complex 1 (MRB1) is a recently discovered complex of proteins associated with the TbRGG1 and TbRGG2 proteins in Trypanosoma brucei. Based on the phenotype caused by down-regulation of these two proteins, it was proposed to play an unspecified role in RNA editing. RNAi silencing of three newly characterized protein subunits, guide RNA associated proteins (GAPs) 1 and 2 as well as a predicted DExD/H-box RNA helicase, show they are essential for cell growth in the procyclic stage. Furthermore, their down-regulation leads to inhibition of editing in only those mRNAs for which minicircle-encoded guide (g) RNAs are required. However, editing remains unaffected when the maxicircle-encoded cis-acting gRNA is employed. Interestingly, all three proteins are necessary for the expression of the minicircle-encoded gRNAs. Moreover, down-regulation of a fourth assayed putative MRB1 subunit, Nudix hydrolase, does not appear to destabilize gRNAs, and down-regulation of this protein has a general impact on the stability of maxicircle-encoded RNAs. GAP1 and 2 are also essential for the survival of the bloodstream stage, in which the gRNAs become eliminated upon depletion of either protein. Immunolocalization revealed that GAP1 and 2 are concentrated into discrete spots along the mitochondrion, usually localized in the proximity of the kinetoplast. Finally, we demonstrate that the same mtRNA polymerase known to transcribe the maxicircle mRNAs may also have a role in expression of the minicircle-encoded gRNAs.
Collapse
Affiliation(s)
- Hassan Hashimi
- Biology Centre, Institute of Parasitology, University of South Bohemia, Ceské Budĕjovice, Budweis, Czech Republic
| | | | | | | | | |
Collapse
|
34
|
Snapshots of the RNA editing machine in trypanosomes captured at different assembly stages in vivo. EMBO J 2009; 28:766-78. [PMID: 19197238 DOI: 10.1038/emboj.2009.19] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Accepted: 01/12/2009] [Indexed: 01/15/2023] Open
Abstract
Mitochondrial pre-messenger RNAs in kinetoplastid protozoa are substrates of uridylate-specific RNA editing. RNA editing converts non-functional pre-mRNAs into translatable molecules and can generate protein diversity by alternative editing. Although several editing complexes have been described, their structure and relationship is unknown. Here, we report the isolation of functionally active RNA editing complexes by a multistep purification procedure. We show that the endogenous isolates contain two subpopulations of approximately 20S and approximately 35-40S and present the three-dimensional structures of both complexes by electron microscopy. The approximately 35-40S complexes consist of a platform density packed against a semispherical element. The approximately 20S complexes are composed of two subdomains connected by an interface. The two particles are structurally related, and we show that RNA binding is a main determinant for the interconversion of the two complexes. The approximately 20S editosomes contain an RNA-binding site, which binds gRNA, pre-mRNA and gRNA/pre-mRNA hybrid molecules with nanomolar affinity. Variability analysis indicates that subsets of complexes lack or possess additional domains, suggesting binding sites for components. Together, a picture of the RNA editing machinery is provided.
Collapse
|
35
|
Niemann M, Kaibel H, Schlüter E, Weitzel K, Brecht M, Göringer HU. Kinetoplastid RNA editing involves a 3' nucleotidyl phosphatase activity. Nucleic Acids Res 2009; 37:1897-906. [PMID: 19190092 PMCID: PMC2665232 DOI: 10.1093/nar/gkp049] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial pre-messenger RNAs (pre-mRNAs) in African trypanosomes require RNA editing in order to mature into functional transcripts. The process involves the addition and/or removal of U nucleotides and is mediated by a high-molecular-mass complex, the editosome. Editosomes catalyze the reaction through an enzyme-driven pathway that includes endo/exoribonuclease, terminal uridylate transferase and RNA ligase activities. Here we show that editing involves an additional reaction step, a 3′ nucleotidyl phosphatase activity. The activity is associated with the editing complex and we demonstrate that the editosomal proteins TbMP99 and TbMP100 contribute to the activity. Both polypeptides contain endo-exonuclease-phosphatase domains and we show that gene ablation of either one of the two polypeptides is compensated by the other protein. However, simultaneous knockdown of both genes results in trypanosome cells with reduced 3′ nucleotidyl phosphatase and reduced editing activity. The data provide a rationale for the exoUase activity of the editosomal protein TbMP42, which generates nonligatable 3′ phosphate termini. Opposing phosphates at the two pre-mRNA cleavage fragments likely function as a roadblock to prevent premature ligation.
Collapse
Affiliation(s)
- Moritz Niemann
- Genetics, Darmstadt University of Technology, Darmstadt, Germany
| | | | | | | | | | | |
Collapse
|
36
|
Weng J, Aphasizheva I, Etheridge RD, Huang L, Wang X, Falick AM, Aphasizhev R. Guide RNA-binding complex from mitochondria of trypanosomatids. Mol Cell 2008; 32:198-209. [PMID: 18951088 PMCID: PMC2645705 DOI: 10.1016/j.molcel.2008.08.023] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2008] [Revised: 07/14/2008] [Accepted: 08/18/2008] [Indexed: 12/16/2022]
Abstract
In the mitochondria of trypanosomatids, the majority of mRNAs undergo massive uracil-insertion/deletion editing. Throughout the processes of pre-mRNA polyadenylation, guide RNA (gRNA) uridylylation and annealing to mRNA, and editing reactions, several multiprotein complexes must engage in transient interactions to produce a template for protein synthesis. Here, we report the identification of a protein complex essential for gRNA stability. The gRNA-binding complex (GRBC) interacts with gRNA processing, editing, and polyadenylation machineries and with the mitochondrial edited mRNA stability (MERS1) factor. RNAi knockdown of the core subunits, GRBC1 and GRBC2, led to the elimination of gRNAs, thus inhibiting mRNA editing. Inhibition of MERS1 expression selectively abrogated edited mRNAs. Homologous proteins unique to the order of Kinetoplastida, GRBC1 and GRBC2, form a stable 200 kDa particle that directly binds gRNAs. Systematic analysis of RNA-mediated and RNA-independent interactions involving the GRBC and MERS1 suggests a unified model for RNA processing in the kinetoplast mitochondria.
Collapse
Affiliation(s)
- James Weng
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Inna Aphasizheva
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Ronald D. Etheridge
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Lan Huang
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Xiaorong Wang
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Arnold M. Falick
- Howard Hughes Medical Institute Mass Spectrometry Laboratory and Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Ruslan Aphasizhev
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| |
Collapse
|
37
|
The KREPA3 zinc finger motifs and OB-fold domain are essential for RNA editing and survival of Trypanosoma brucei. Mol Cell Biol 2008; 28:6939-53. [PMID: 18794366 DOI: 10.1128/mcb.01115-08] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Three types of editosomes, each with an identical core containing six related KREPA proteins, catalyze the U insertion and deletion RNA editing of mitochondrial mRNAs in trypanosomes. Repression of expression of one of these, KREPA3 (also known as TbMP42), shows that it is essential for growth and in vivo editing in both procyclic (PF) and bloodstream (BF) life cycle stages of Trypanosoma brucei. RNA interference knockdown results in editosome disruption and altered in vitro editing in PFs, while repression by regulatable double knockout results in almost complete loss of editosomes in BFs. Mutational analysis shows that the KREPA3 zinc fingers and OB-fold domain are each essential for growth and in vivo editing. Nevertheless, KREPA3 with mutated zinc fingers incorporates into editosomes that catalyze in vitro editing and thus is not essential for editosome integrity, although stability is affected. In contrast, the OB-fold domain is essential for editosome integrity. Overall, KREPA3, especially its OB-fold, functions in editosome integrity, and its zinc fingers are essential for editing in vivo but not for the central catalytic steps. KREPA3 may function in editosome organization and/or RNA positioning.
Collapse
|
38
|
Niemann M, Brecht M, Schlüter E, Weitzel K, Zacharias M, Göringer HU. TbMP42 is a structure-sensitive ribonuclease that likely follows a metal ion catalysis mechanism. Nucleic Acids Res 2008; 36:4465-73. [PMID: 18603593 PMCID: PMC2490751 DOI: 10.1093/nar/gkn410] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 06/10/2008] [Accepted: 06/10/2008] [Indexed: 12/22/2022] Open
Abstract
RNA editing in African trypanosomes is characterized by a uridylate-specific insertion and/or deletion reaction that generates functional mitochondrial transcripts. The process is catalyzed by a multi-enzyme complex, the editosome, which consists of approximately 20 proteins. While for some of the polypeptides a contribution to the editing reaction can be deduced from their domain structure, the involvement of other proteins remains elusive. TbMP42, is a component of the editosome that is characterized by two C(2)H(2)-type zinc-finger domains and a putative oligosaccharide/oligonucleotide-binding fold. Recombinant TbMP42 has been shown to possess endo/exoribonuclease activity in vitro; however, the protein lacks canonical nuclease motifs. Using a set of synthetic gRNA/pre-mRNA substrate RNAs, we demonstrate that TbMP42 acts as a topology-dependent ribonuclease that is sensitive to base stacking. We further show that the chelation of Zn(2+) cations is inhibitory to the enzyme activity and that the chemical modification of amino acids known to coordinate Zn(2+) inactivates rTbMP42. Together, the data are suggestive of a Zn(2+)-dependent metal ion catalysis mechanism for the ribonucleolytic activity of rTbMP42.
Collapse
Affiliation(s)
- Moritz Niemann
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Michael Brecht
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Elke Schlüter
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Kerstin Weitzel
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Martin Zacharias
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - H. Ulrich Göringer
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| |
Collapse
|
39
|
Zíková A, Kopečná J, Schumacher MA, Stuart K, Trantírek L, Lukeš J. Structure and function of the native and recombinant mitochondrial MRP1/MRP2 complex from Trypanosoma brucei. Int J Parasitol 2008; 38:901-12. [PMID: 18295767 PMCID: PMC2492832 DOI: 10.1016/j.ijpara.2007.12.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 12/19/2007] [Accepted: 12/31/2007] [Indexed: 10/22/2022]
Abstract
The mitochondrial RNA-binding proteins (MRP) 1 and 2 play a regulatory role in RNA editing and putative role(s) in RNA processing in Trypanosoma brucei. Here, we report the purification of a high molecular weight protein complex consisting solely of the MRP1 and MRP2 proteins from the mitochondrion of T. brucei. The MRP1/MRP2 complex natively purified from T. brucei and the one reconstituted in Escherichia coli in vivo bind guide (g) RNAs and pre-mRNAs with dissociation constants in the nanomolar range, and efficiently promote annealing of pre-mRNAs with their cognate gRNAs. In addition, the MRP1/MRP2 complex stimulates annealing between two non-cognate RNA molecules suggesting that along with the cognate duplexes, spuriously mismatched RNA hybrids may be formed at some rate in vivo. A mechanism of catalysed annealing of gRNA/pre-mRNA by the MRP1/MRP2 complex is proposed.
Collapse
Affiliation(s)
- Alena Zíková
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
- Seattle Biomedical Research Institute, Seattle, USA
| | - Jana Kopečná
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Maria A. Schumacher
- Department of Biochemistry and Molecular Biology, University of Texas, M.D. Anderson Cancer Center, Houston, USA
| | | | - Lukáš Trantírek
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| |
Collapse
|
40
|
Law JA, O'Hearn SF, Sollner-Webb B. Trypanosoma brucei RNA editing protein TbMP42 (band VI) is crucial for the endonucleolytic cleavages but not the subsequent steps of U-deletion and U-insertion. RNA (NEW YORK, N.Y.) 2008; 14:1187-200. [PMID: 18441050 PMCID: PMC2390806 DOI: 10.1261/rna.899508] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 02/18/2008] [Indexed: 05/20/2023]
Abstract
Trypanosome mitochondrial mRNAs achieve their coding sequences through RNA editing. This process, catalyzed by approximately 20S protein complexes, involves large numbers of uridylate (U) insertions and deletions within mRNA precursors. Here we analyze the role of the essential TbMP42 protein (band VI/KREPA2) by individually examining each step of the U-deletional and U-insertional editing cycles, using reactions in the approximately linear range. We examined control extracts and RNA interference (RNAi) extracts prepared soon after TbMP42 was depleted (when primary effects should be most evident) and three days later (when precedent shows secondary effects can become prominent). This analysis shows TbMP42 is critical for cleavage of editing substrates by both the U-deletional and U-insertional endonucleases. However, on simple substrates that assess cleavage independent of editing features, TbMP42 is similarly required only for the U-deletional endonuclease, indicating TbMP42 affects the two editing endonucleases differently. Supplementing RNAi extract with recombinant TbMP42 partly restores these cleavage activities. Notably, we find that all the other editing steps (the 3'-U-exonuclease [3'-U-exo] and ligation steps of U-deletion and the terminal-U-transferase [TUTase] and ligation steps of U-insertion) remain at control levels upon RNAi induction, and hence are not dependent on TbMP42. This contrasts with an earlier report that TbMP42 is a 3'-U-exo that may act in U-deletion and additionally is critical for the TUTase and/or ligation steps of U-insertion, observations our data suggest reflect indirect effects of TbMP42 depletion. Thus, trypanosomes require TbMP42 for both endonucleolytic cleavage steps of RNA editing, but not for any of the subsequent steps of the editing cycles.
Collapse
Affiliation(s)
- Julie A Law
- Biological Chemistry Department, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | | |
Collapse
|
41
|
Ammerman ML, Fisk JC, Read LK. gRNA/pre-mRNA annealing and RNA chaperone activities of RBP16. RNA (NEW YORK, N.Y.) 2008; 14:1069-80. [PMID: 18441045 PMCID: PMC2390797 DOI: 10.1261/rna.982908] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 02/29/2008] [Indexed: 05/08/2023]
Abstract
Editing in trypanosomes involves the addition or deletion of uridines at specific sites to produce translatable mitochondrial mRNAs. RBP16 is an accessory factor from Trypanosoma brucei that affects mitochondrial RNA editing in vivo and also stimulates editing in vitro. We report here experiments aimed at elucidating the biochemical activities of RBP16 involved in modulating RNA editing. In vitro RNA annealing assays demonstrate that RBP16 significantly stimulates the annealing of gRNAs to cognate pre-mRNAs. In addition, RBP16 also facilitates hybridization of partially complementary RNAs unrelated to the editing process. The RNA annealing activity of RBP16 is independent of its high-affinity binding to gRNA oligo(U) tails, consistent with the previously reported in vitro editing stimulatory properties of the protein. In vivo studies expressing recombinant RBP16 in mutant Escherichia coli strains demonstrate that RBP16 is an RNA chaperone and that in addition to RNA annealing activity, it contains RNA unwinding activity. Our data suggest that the mechanism by which RBP16 facilitates RNA editing involves its capacity to modulate RNA secondary structure and promote gRNA/pre-mRNA annealing.
Collapse
Affiliation(s)
- Michelle L Ammerman
- Department of Microbiology and Immunology, School of Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | | | | |
Collapse
|
42
|
Homann M. Editing Reactions from the Perspective of RNA Structure. NUCLEIC ACIDS AND MOLECULAR BIOLOGY 2008. [DOI: 10.1007/978-3-540-73787-2_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
43
|
Göringer HU, Brecht M, Böhm C, Kruse E. RNA Editing Accessory Factors — the Example of mHel61p. NUCLEIC ACIDS AND MOLECULAR BIOLOGY 2008. [DOI: 10.1007/978-3-540-73787-2_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
|
44
|
Aphasizhev R, Aphasizheva I. Terminal RNA uridylyltransferases of trypanosomes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2007; 1779:270-80. [PMID: 18191648 DOI: 10.1016/j.bbagrm.2007.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 12/10/2007] [Accepted: 12/13/2007] [Indexed: 12/14/2022]
Abstract
Terminal RNA uridylyltransferases (TUTases) are functionally and structurally diverse nucleotidyl transferases that catalyze template-independent 3' uridylylation of RNAs. Within the DNA polymerase beta-type superfamily, TUTases are closely related to non-canonical poly(A) polymerases. Studies of U-insertion/deletion RNA editing in mitochondria of trypanosomatids identified the first TUTase proteins and their cellular functions: post-transcriptional uridylylation of guide RNAs by RNA editing TUTase 1 (RET1) and U-insertion mRNA editing by RNA editing TUTase 2 (RET2). The editing TUTases possess conserved catalytic and nucleotide base recognition domains, yet differ in quaternary structure, substrate specificity and processivity. The cytosolic TUTases TUT3 and TUT4 have also been identified in trypanosomes but their biological roles remain to be established. Structural analyses have revealed a mechanism of cognate nucleoside triphosphate selection by TUTases, which includes protein-UTP contacts as well as contribution of the RNA substrate. This review focuses on biological functions and structures of trypanosomal TUTases.
Collapse
Affiliation(s)
- Ruslan Aphasizhev
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4025, USA.
| | | |
Collapse
|
45
|
Abstract
Multisubunit RNA editing complexes recognize thousands of pre-mRNA sites in the single mitochondrion of trypanosomes. Specific determinants at each editing site must trigger the complexes to catalyze a complete cycle of either uridylate insertion or deletion. While a wealth of information on the protein composition and catalytic activities of these complexes is currently available, the precise mechanisms that govern substrate recognition and editing site specificity remain unknown. This chapter describes basic assays to visualize direct photocrosslinking interactions between purified editing complexes and targeted deletion and insertion sites in model substrates for full-round editing. It also illustrates how variations of these assays can be applied to examine the specificity of the editing enzyme/substrate association, and to dissect structural or biochemical requirements of both the substrates and enzyme complex.
Collapse
Affiliation(s)
- Jorge Cruz-Reyes
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, USA
| |
Collapse
|
46
|
|
47
|
Cifuentes-Rojas C, Pavia P, Hernandez A, Osterwisch D, Puerta C, Cruz-Reyes J. Substrate determinants for RNA editing and editing complex interactions at a site for full-round U insertion. J Biol Chem 2007; 282:4265-4276. [PMID: 17158098 DOI: 10.1074/jbc.m605554200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Multisubunit RNA editing complexes catalyze uridylate insertion/deletion RNA editing directed by complementary guide RNAs (gRNAs). Editing in trypanosome mitochondria is transcript-specific and developmentally controlled, but the molecular mechanisms of substrate specificity remain unknown. Here we used a minimal A6 pre-mRNA/gRNA substrate to define functional determinants for full-round insertion and editing complex interactions at the editing site 2 (ES2). Editing begins with pre-mRNA cleavage within an internal loop flanked by upstream and downstream duplexes with gRNA. We found that substrate recognition around the internal loop is sequence-independent and that completely artificial duplexes spanning a single helical turn are functional. Furthermore, after our report of cross-linking interactions at the deletion ES1 (35), we show for the first time editing complex contacts at an insertion ES. Our studies using site-specific ribose 2' substitutions defined 2'-hydroxyls within the (a) gRNA loop region and (b) flanking helixes that markedly stimulate both pre-mRNA cleavage and editing complex interactions at ES2. Modification of the downstream helix affected scissile bond specificity. Notably, a single 2'-hydroxyl at ES2 is essential for cleavage but dispensable for editing complex cross-linking. This study provides new insights on substrate recognition during full-round editing, including the relevance of secondary structure and the first functional association of specific (pre-mRNA and gRNA) riboses with both endonuclease cleavage and cross-linking activities of editing complexes at an ES. Importantly, most observed cross-linking interactions are both conserved and relatively stable at ES2 and ES1 in hybrid substrates. However, they were also detected as transient low-stability contacts in a non-edited transcript.
Collapse
Affiliation(s)
| | - Paula Pavia
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843 and
| | - Alfredo Hernandez
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843 and
| | - Daniel Osterwisch
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843 and
| | - Concepcion Puerta
- Laboratorio of Parasitologia Molecular, Pontificia Universidad Javeriana, Carrera 7a No. 43-82, Ed. 50, Lab 113, Bogota´, Colombia
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843 and.
| |
Collapse
|
48
|
Pelletier M, Read LK, Aphasizhev R. Isolation of RNA binding proteins involved in insertion/deletion editing. Methods Enzymol 2007; 424:75-105. [PMID: 17662837 DOI: 10.1016/s0076-6879(07)24004-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
RNA editing is a collective term referring to a plethora of reactions that ultimately lead to changes in RNA nucleotide sequences apart from splicing, 5' capping, or 3' end processing. In the mitochondria of trypanosomatids, insertion and deletion of uridines must occur, often on a massive scale, in order to generate functional messenger RNAs. The current state of knowledge perceives the editing machinery as a dynamic system, in which heterogeneous protein complexes undergo multiple transient RNA-protein interactions in the course of gRNA processing, gRNA-mRNA recognition, and the cascade of nucleolytic and phosphoryl transfer reactions that ultimately change the mRNA sequence. Identification of RNA binding proteins that interact with the mitochondrial RNAs, core editing complex, or contribute to mRNA stability is of critical importance to our understanding of the editing process. This chapter describes purification and characterization of three RNA binding proteins from kinetoplastid mitochondria that have been genetically demonstrated to affect RNA editing.
Collapse
Affiliation(s)
- Michel Pelletier
- Department of Microbiology and Immunology, SUNY Buffalo School of Medicine, Buffalo, New York, USA
| | | | | |
Collapse
|
49
|
Halbig K, Sacharidou A, De Nova-Ocampo M, Cruz-Reyes J. Preferential interaction of a 25kDa protein with an A6 pre-mRNA substrate for RNA editing in Trypanosoma brucei. Int J Parasitol 2006; 36:1295-304. [PMID: 16860325 DOI: 10.1016/j.ijpara.2006.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 05/14/2006] [Accepted: 05/15/2006] [Indexed: 11/23/2022]
Abstract
Mitochondrial gene expression in kinetoplastids is controlled after transcription, potentially at the levels of RNA maturation, stability and translation. Among these processes, RNA editing by U-insertion/deletion catalysed by multi-subunit editing complexes is best characterised at the molecular level. Nevertheless, mitochondrial RNA metabolism overall remains poorly understood, including the potential regulatory factors that may interact with the relevant catalytic molecular machines and/or RNA substrates. Here we report on a approximately 25kDa polypeptide in mitochondrial extracts that exhibits a preferential "zero-distance" photo-crosslinking interaction with an A6 pre-mRNA model substrate for RNA editing containing a single [(32)P] at the first editing site. The approximately 25kDa polypeptide purified away from editosomes upon ion-exchange chromatography and glycerol gradient sedimentation. Competition assays with homologous and heterologous transcripts suggest that the preferential recognition of the A6 substrate is based on relatively low-specificity RNA-protein contacts. Our mapping and substrate truncation analyses suggest that the crosslinking activity primarily targeted a predicted stem-loop region containing the first editing sites. Consistent with the notion that pre-mRNA folding may be required, pre-annealing with guide RNA abolished crosslinking. Interestingly, this preferential protein interaction with the A6 substrate seemed to require adenosine 5'-triphosphate but not hydrolysis. As in other biological systems, fine regulation in vivo may be brought about by transient networks of relatively low-specificity interactions in which multiple auxiliary factors bind to mRNAs and/or editing complexes in unique higher-order assemblies.
Collapse
Affiliation(s)
- Kari Halbig
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843, USA
| | | | | | | |
Collapse
|
50
|
Schumacher MA, Karamooz E, Zíková A, Trantírek L, Lukes J. Crystal structures of T. brucei MRP1/MRP2 guide-RNA binding complex reveal RNA matchmaking mechanism. Cell 2006; 126:701-11. [PMID: 16923390 DOI: 10.1016/j.cell.2006.06.047] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Revised: 05/19/2006] [Accepted: 06/23/2006] [Indexed: 11/19/2022]
Abstract
The mitochondrial RNA binding proteins MRP1 and MRP2 form a heteromeric complex that functions in kinetoplastid RNA editing. In this process, MRP1/MRP2 serves as a matchmaker by binding to guide RNAs and facilitating their hybridization with cognate preedited mRNAs. To understand the mechanism by which this complex performs RNA matchmaking, we determined structures of Trypanosoma brucei apoMRP1/MRP2 and an MRP1/MRP2-gRNA complex. The structures show that MRP1/MRP2 is a heterotetramer and, despite little sequence homology, each MRP subunit exhibits the same "Whirly" transcription-factor fold. The gRNA molecule binds to the highly basic beta sheet surface of the MRP complex via nonspecific, electrostatic contacts. Strikingly, while the gRNA stem/loop II base is anchored to the basic surface, stem/loop I (the anchor sequence) is unfolded and its bases exposed to solvent. Thus, MRP1/MRP2 acts as an RNA matchmaker by stabilizing the RNA molecule in an unfolded conformation suitable for RNA-RNA hybridization.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Crystallography, X-Ray
- Mitochondrial Proteins/chemistry
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Binding
- Protein Folding
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Sequence Alignment
- Trypanosoma brucei brucei/chemistry
- Trypanosoma brucei brucei/metabolism
Collapse
Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry and Molecular Biology, University of Texas, M.D. Anderson Cancer Center, Unit 1000, Houston, 77030, USA.
| | | | | | | | | |
Collapse
|